It’s not obnoxious to ask what your server recommends, but it is a bit rude to then ignore their advice. It’s one thing to order what you like if the server makes a few recommendations unprompted, but if you ask for their advice, it’s sort of odd not to take it.
Often, one doesn’t take the advice of their server because asking for it in the first place is simply a reflex. Asking the question, “What’s good here?” seems a lot like saying “hello.” But the problem with that is you aren’t just saying hi — you’re literally asking the person serving you to tell you what’s good, and then openly flouting that advice by ordering something completely different. It feels like a snub to the waiter at worst and a waste of their time at best.
If something is on the menu, it’s because the restaurant believes it to be good. No self-respecting dining establishment hides terrible dishes on the menu in the hopes of someone ordering one — GOTCHA! So if you see something that strikes your fancy, place the order. If you don’t, feel free to ask for some advice, but before you do, be sure to let the server know what you do and don’t like to begin with. That way, they won’t recommend the chicken when you were really in the mood for steak.